Going wild: a visit to Knepp
By Deborah Spring
For the past twenty years Isabella Tree and her husband Charlie Burrell have let nature take over their estate at Knepp in Sussex, with the intention of ‘rewilding’ the whole 3500 acres. Today rare species live and breed in meadow and woodland, formerly arable fields. The project is chronicled in Isabella Tree’s book Wilding (2018).
More recently they have begun a radical redesign of their garden. Stephen and I visited Knepp for a morning’s ‘garden safari’ on a hot day in August this year. The forty-three million gardens in the UK comprise four times the land mass of our nature reserves. At Knepp they are asking: What can we do to make best use of this resource for nature and encourage biodiversity? How will gardening change as our climate changes? For the past three years at Knepp the gardeners have been experimenting, and in the words of deputy head gardener Moy, ‘gardening like herbivores’. In nature, she explained, landscapes are disturbed in many ways including animals digging and browsing, drought or flood. Added to stresses such as the shortage or excess of resources, this disturbance increases diversity as plants respond to changes in their environments. This in turn increases the opportunities for plants to thrive. When gardening, we take the place of the browsing and rootling fauna that are absent from our garden landscapes – digging, weeding, harvesting and cutting back. We also seek to minimise threats to our plants and maximise productivity, creating level growing areas with enriched soil and watering our choice specimens. With climate change and species depletion already evident, should we start to plan differently for our gardens? Similar questions were highlighted in several show garden designs this year at Chelsea. The Knepp experiment explores what a rewilded garden could be like and how principles developed over the thousands of acres of the estate might be adapted for those of us who connect with nature through our gardens. To begin our safari Matt the ecologist took us into the orchard, where he had set moth traps the night before. His catch included a magnificent hawkshead moth as well as many smaller ones. Orchards are very biodiverse, he explained, and this is good news for insects. Piles of brash make good habitats, buried wood encourages beetles and fallen fruit is food for insects. Ant hills are part of the ecosystem and provide food for birds. Moths and butterflies are among the best pollinators - and more pollination happens at night than during the day - and deal with waste disposal, clearing nests, for example. Huge numbers of tiny ‘micromoths’ live in long grass. Cutting grass cyclically in early spring and August/September gives the best opportunities for insect and bird life to thrive. In this orchard thistles are left to provide food for goldfinches, and borage for bees, while birdsfoot trefoil helps with nitrogen fixing and importantly, is good for moths and butterflies to lay eggs on (other butterfly-friendly plants such as buddleia may only be a food source, and insects need the right place to lay eggs as well). Moy led us to the walled garden past a mature beech hedge that had been cut into random dips and curves to vary the habitat for insects and birds. The formerly traditional vegetable garden has been adapted, with a shift in emphasis to herbs and a wider diversity of fruit and vegetables grown in small quantities in no-dig beds. Crushed limestone paths are partly colonised by thyme, fennel and other herbs, and the late summer harvest included courgettes, squashes, beans and tomatoes. A sunny wall was given over to a substantial bee hotel and other insect sanctuaries. Water was collected in a central tank. The overall effect was informal, a bit messy, and abundant. |
Flat land is not normal
The most dramatic changes have been made in the next part of the walled garden, previously a formal arrangement of immaculately kept croquet lawn and swimming pool. But, we were told, flat land is not normal: nature is uneven – wet hollows rise into sunny banks, soil is varied in its structure – and the more complex the structure of a landscape, even a small-scale one, the greater the biodiversity. This principle was the project’s starting point, and the croquet lawn was comprehensively dug up and recontoured. With a variation of one-and-a-half metres above and below the old lawn level, some parts are now seasonally flooded. Tom Stuart-Smith masterminded the new structure, working with James Hitchmough, a professor of horticultural ecology, to further diversify the landscape by varying the soil fertility of different areas. An eight-inch layer of crushed concrete and sand forms a substrate for plants that would be outcompeted on ordinary soil. In other places sand alone is used as a mulch. This is not an exercise in limiting the garden to native species: Hitchmough has introduced plants from dry climates across the world, mixing them in with each other in contrast to the central areas laid out by Tom with plants in informal blocks. There are no hybrids – plants will reproduce themselves - and while it is not being gardened in the way we are used to, the gardeners can selectively remove and cut back where they choose to nudge the garden in a desired direction. We left Knepp with a better understanding of the garden as an ecosystem, and some ideas about how we can do more in our own garden to promote insect and bird life and sustainability. The Knepp experiment is not something to be copied wholesale but for us it has shaken up our ideas and made us look differently at the potential of our new garden. The good news is that through small changes to our gardening habits now, we can choose to make a difference to the sustainability of our gardens - and the health of the planet. Our key ‘takeaways’ from Knepp include: • Leave messy corners– a ‘weedy’ patch with lumps and bumps and some wood left to rot down is wonderful for insect life and supports the local ecosystem. It doesn’t have to be in full view! • Let some grass and wildflowers grow long, only cutting in spring and August/September. Even a small patch helps. • Use permeable surfaces and explore alternative materials and methods for creating paths, patios and driveways. • Experiment with drought-tolerant plants to reduce watering and improve survival in hot summers. • Grow some native plants with blossom for pollinators and fruit/berries for birds. Leave seed heads on perennials for the birds, rather than cutting them down after flowering. • Encourage insects and other wildlife with a bug hotel. You can make your own using leftover wood, sticks and stems from around the garden, or buy one from the RSPB. |